The differential contribution of pacemaker neurons to synaptic transmission in the pyloric network of the Jonah crab, Cancer borealis.

Many neurons receive synchronous input from heterogeneous presynaptic neurons with distinct properties. An instructive example is the crustacean stomatogastric pyloric circuit pacemaker group, consisting of the anterior burster (AB) and pyloric dilator (PD) neurons, which are active synchronously and exert a combined synaptic action on most pyloric follower neurons. Previous studies in lobster have indicated that AB is glutamatergic, whereas PD is cholinergic. However, although the stomatogastric system of the crab Cancer borealis has become a preferred system for exploration of cellular and synaptic basis of circuit dynamics, the pacemaker synaptic output has not been carefully analyzed in this species. We examined the synaptic properties of these neurons using a combination of single-cell mRNA analysis, electrophysiology, and pharmacology. The crab PD neuron expresses high levels of choline acetyltransferase and the vesicular acetylcholine transporter mRNAs, hallmarks of cholinergic neurons. In contrast, the AB neuron expresses neither cholinergic marker but expresses high levels of vesicular glutamate transporter mRNA, consistent with a glutamatergic phenotype. Notably, in the combined synapses to follower neurons, 70-75% of the total current was blocked by putative glutamatergic blockers, but short-term synaptic plasticity remained unchanged, and although the total pacemaker current in two follower neuron types was different, this difference did not contribute to the phasing of the follower neurons. These findings provide a guide for similar explorations of heterogeneous synaptic connections in other systems and a baseline in this system for the exploration of the differential influence of neuromodulators.NEW & NOTEWORTHY The pacemaker-driven pyloric circuit of the Jonah crab stomatogastric nervous system is a well-studied model system for exploring circuit dynamics and neuromodulation, yet the understanding of the synaptic properties of the two pacemaker neuron types is based on older analyses in other species. We use single-cell PCR and electrophysiology to explore the neurotransmitters used by the pacemaker neurons and their distinct contribution to the combined synaptic potentials.

Short-term synaptic dynamics control the activity phase of neurons in an oscillatory network.

In oscillatory systems, neuronal activity phase is often independent of network frequency. Such phase maintenance requires adjustment of synaptic input with network frequency, a relationship that we explored using the crab, Cancer borealis, pyloric network. The burst phase of pyloric neurons is relatively constant despite a > two fold variation in network frequency. We used noise input to characterize how input shape influences burst delay of a pyloric neuron, and then used dynamic clamp to examine how burst phase depends on the period, amplitude, duration, and shape of rhythmic synaptic input. Phase constancy across a range of periods required a proportional increase of synaptic duration with period. However, phase maintenance was also promoted by an increase of amplitude and peak phase of synaptic input with period. Mathematical analysis shows how short-term synaptic plasticity can coordinately change amplitude and peak phase to maximize the range of periods over which phase constancy is achieved.

Similarities and differences in circuit responses to applied Gly1-SIFamide and peptidergic (Gly1-SIFamide) neuron stimulation.

Microcircuit modulation by peptides is well established, but the cellular/synaptic mechanisms whereby identified neurons with identified peptide transmitters modulate microcircuits remain unknown for most systems. Here, we describe the distribution of GYRKPPFNGSIFamide (Gly1-SIFamide) immunoreactivity (Gly1-SIFamide-IR) in the stomatogastric nervous system (STNS) of the crab Cancer borealis and the Gly1-SIFamide actions on the two feeding-related circuits in the stomatogastric ganglion (STG). Gly1-SIFamide-IR localized to somata in the paired commissural ganglia (CoGs), two axons in the nerves connecting each CoG with the STG, and the CoG and STG neuropil. We identified one Gly1-SIFamide-IR projection neuron innervating the STG as the previously identified modulatory commissural neuron 5 (MCN5). Brief (~10 s) MCN5 stimulation excites some pyloric circuit neurons. We now find that bath applying Gly1-SIFamide to the isolated STG also enhanced pyloric rhythm activity and activated an imperfectly coordinated gastric mill rhythm that included unusually prolonged bursts in two circuit neurons [inferior cardiac (IC), lateral posterior gastric (LPG)]. Furthermore, longer duration (>30 s) MCN5 stimulation activated a Gly1-SIFamide-like gastric mill rhythm, including prolonged IC and LPG bursting. The prolonged LPG bursting decreased the coincidence of its activity with neurons to which it is electrically coupled. We also identified local circuit feedback onto the MCN5 axon terminals, which may contribute to some distinctions between the responses to MCN5 stimulation and Gly1-SIFamide application. Thus, MCN5 adds to the few identified projection neurons that modulate a well-defined circuit at least partly via an identified neuropeptide transmitter and provides an opportunity to study peptide regulation of electrical coupled neurons in a functional context. NEW & NOTEWORTHY Limited insight exists regarding how identified peptidergic neurons modulate microcircuits. We show that the modulatory projection neuron modulatory commissural neuron 5 (MCN5) is peptidergic, containing Gly1-SIFamide. MCN5 and Gly1-SIFamide elicit similar output from two well-defined motor circuits. Their distinct actions may result partly from circuit feedback onto the MCN5 axon terminals. Their similar actions include eliciting divergent activity patterns in normally coactive, electrically coupled neurons, providing an opportunity to examine peptide modulation of electrically coupled neurons in a functional context.

Two central pattern generators from the crab, Cancer borealis, respond robustly and differentially to extreme extracellular pH.

The activity of neuronal circuits depends on the properties of the constituent neurons and their underlying synaptic and intrinsic currents. We describe the effects of extreme changes in extracellular pH - from pH 5.5 to 10.4 - on two central pattern generating networks, the stomatogastric and cardiac ganglia of the crab, Cancer borealis. Given that the physiological properties of ion channels are known to be sensitive to pH within the range tested, it is surprising that these rhythms generally remained robust from pH 6.1 to pH 8.8. The pH sensitivity of these rhythms was highly variable between animals and, unexpectedly, between ganglia. Animal-to-animal variability was likely a consequence of similar network performance arising from variable sets of underlying conductances. Together, these results illustrate the potential difficulty in generalizing the effects of environmental perturbation across circuits, even within the same animal.

Preservation of the celiac branch of the vagal nerve for pylorus-preserving gastrectomy: is it meaningful?

BACKGROUND: Preserving the hepatic and pyloric branches of the vagal nerve in laparoscopic pylorus-preserving gastrectomy (LPPG) is considered necessary to maintain the function of the pyloric cuff. However, the clinical benefits of preservation of the celiac branch of the vagal nerve (CBVN) remain unclear. METHODS: Of 391 patients who underwent LPPG for early gastric cancer, 116 patients in whom the CBVN was preserved (CBP group) and 58 patients in whom it was not preserved (non-CBP group) were selected through the propensity score-matching method. To evaluate the surgical and oncological safety of preserving the CBVN, postoperative morbidity and mortality were analyzed between these matched groups. Postoperative nutritional status, body weight changes, endoscopic findings, and the incidence of gallstones were compared to evaluate any functional advantages. RESULTS: The short-term surgical outcomes in the CBP group were similar to those in the non-CBP group. The number of dissected lymph nodes did not differ (34 vs. 33.5, P = 0.457), and the 5-year recurrence-free survival rates were also similar between both groups (99.1% vs. 97.1%, P = 0.844). There were no significant differences in postoperative nutritional status, body weight changes, or the incidence of gallstones. By endoscopy, 1 year after surgery residual food was frequently observed in both groups; however, there were no significant differences in the frequency of remnant gastritis and esophageal and bile reflux. CONCLUSIONS: Preserving CBVN in LPPG for early gastric cancer is a feasible procedure. However, no clinical benefits of the preservation of the CBVN after LPPG are identified.

[Value of endoscopy application in the management of complications after radical gastrectomy for gastric cancer].

Endoscopy plays an important role in the diagnosis and treatment of postoperative complications of gastric cancer. Endoscopic intervention can avoid the second operation and has attracted wide attention. Early gastric anastomotic bleeding after gastrectomy is the most common. With the development of technology, emergency endoscopy and endoscopic hemostasis provide a new treatment approach. According to the specific circumstances, endoscopists can choose metal clamp to stop bleeding, electrocoagulation hemostasis, local injection of epinephrine or sclerotherapy agents, and spraying specific hemostatic agents. Anastomotic fistula is a serious postoperative complication. In addition to endoscopically placing the small intestine nutrition tube for early enteral nutrition support treatment, endoscopic treatment, including stent, metal clip, OTSC, and Over-stitch suture system, can be chosen to close fistula. For anastomotic obstruction or stricture, endoscopic balloon or probe expansion and stent placement can be chosen. For esophageal anastomotic intractable obstruction after gastroesophageal surgery, radial incision of obstruction by the hook knife or IT knife, a new method named ERI, is a good choice. Bile leakage caused by bile duct injury can be treated by placing the stent or nasal bile duct. In addition, endoscopic methods are widely used as follows: abdominal abscess can be treated by the direct intervention under endoscopy; adhesive ileus can be treated by placing the catheter under the guidance of endoscopy to attract pressure; alkaline reflux gastritis can be rapidly diagnosed by endoscopy; gastric outlet obstruction mainly caused by cancer recurrence can be relieved by metal stent placement and the combination of endoscopy and X-ray can increase success rate; pyloric dysfunction and spasm caused by the vagus nerve injury during proximal gastrectomy can be treated by endoscopic pyloromyotomy, a new method named G-POEM, and the short-term outcomes are significant. Endoscopic submucosal dissection (ESD) allows complete resection of residual gastric precancerous lesions, however it should be performed by the experienced endoscopists.

Neuropeptide profile changes in sensory neurones after partial prepyloric resection in pigs.

This report details the first identification of the sources of sensory innervation of the porcine stomach prepyloric region. The Fast Blue (FB) retrograde tracing technique detected the sensory prepyloric neurons in the bilateral nodose ganglia (NGs) as well as thoracic dorsal root ganglia (DRGs). Double-labelling immunofluorescence demonstrated expression of substance P (SP), calcitonin gene-related peptide (CGRP), neuronal isoform of nitric oxide synthase (nNOS), vasoactive intestinal polypeptide (VIP) and galanin (GAL) in both NGs and DRGs. Additionally, we found that partial resection of the stomach prepyloric area increased expression of the SP, CGRP, NOS, VIP and GAL in the prepyloric sensory neurons. In the control left NGs, both a higher total number of FB-positive perikarya as well as a higher percentage of the peptides expressing prepyloric neurons were visualized than in the right NGs. However, compared to the control group, prepyloric resection evoked greater increases in peptide expression in the right-side NGs sensory neurons. In the ganglia of this side, the proportion of the SP-IR perikarya increased by approximately 15%, while CGRP-IR increased by 28%, NOS-IR 14%, VIP-IR 43% and GAL-IR 13%. On the opposite left side, the ganglia proportion of the CGRP-IR perikarya increased by approximately 10%, while NOS-IR increased by 3%, VIP-IR 36% and GAL-IR by 2%. The only decrease (by 5%) was observed in the case of SP expression. We also found that 92% of the sensory neurons originated from NGs and 8% from DRGs. Our results indicate that, in the pig, SP, CGRP, NOS, VIP and GAL participate in the vagal sensory transduction from the stomach prepyloric area. Moreover, increased expression of the peptides and neuronal isoform of nitric oxide synthase in the sensory neurons following transection of their peripheral dendrites suggests their possible participation in the neuronal recovery and/or reinnervation process.

Incorporating spike-rate adaptation into a rate code in mathematical and biological neurons.

For a slowly varying stimulus, the simplest relationship between a neuron's input and output is a rate code, in which the spike rate is a unique function of the stimulus at that instant. In the case of spike-rate adaptation, there is no unique relationship between input and output, because the spike rate at any time depends both on the instantaneous stimulus and on prior spiking (the "history"). To improve the decoding of spike trains produced by neurons that show spike-rate adaptation, we developed a simple scheme that incorporates "history" into a rate code. We utilized this rate-history code successfully to decode spike trains produced by 1) mathematical models of a neuron in which the mechanism for adaptation (IAHP) is specified, and 2) the gastropyloric receptor (GPR2), a stretch-sensitive neuron in the stomatogastric nervous system of the crab Cancer borealis, that exhibits long-lasting adaptation of unknown origin. Moreover, when we modified the spike rate either mathematically in a model system or by applying neuromodulatory agents to the experimental system, we found that changes in the rate-history code could be related to the biophysical mechanisms responsible for altering the spiking.

Role of Ih in differentiating the dynamics of the gastric and pyloric neurons in the stomatogastric ganglion of the lobster, Homarus americanus.

The hyperpolarization-activated inward cationic current (Ih) is known to regulate the rhythmicity, excitability, and synaptic transmission in heart cells and many types of neurons across a variety of species, including some pyloric and gastric mill neurons in the stomatogastric ganglion (STG) in Cancer borealis and Panulirus interruptus However, little is known about the role of Ih in regulating the gastric mill dynamics and its contribution to the dynamical bifurcation of the gastric mill and pyloric networks. We investigated the role of Ih in the rhythmic activity and cellular excitability of both the gastric mill neurons (medial gastric, gastric mill) and pyloric neurons (pyloric dilator, lateral pyloric) in Homarus americanus Through testing the burst period between 5 and 50 mM CsCl, and elimination of postinhibitory rebound and voltage sag, we found that 30 mM CsCl can sufficiently block Ih in both the pyloric and gastric mill neurons. Our results show that Ih maintains the excitability of both the pyloric and gastric mill neurons. However, Ih regulates slow oscillations of the pyloric and gastric mill neurons differently. Specifically, blocking Ih diminishes the difference between the pyloric and gastric mill burst periods by increasing the pyloric burst period and decreasing the gastric mill burst period. Moreover, the phase-plane analysis shows that blocking Ih causes the trajectory of slow oscillations of the gastric mill neurons to change toward the pyloric sinusoidal-like trajectories. In addition to regulating the pyloric rhythm, we found that Ih is also essential for the gastric mill rhythms and differentially regulates these two dynamics.

Alterations of neurochemical expression of the coeliac-superior mesenteric ganglion complex (CSMG) neurons supplying the prepyloric region of the porcine stomach following partial stomach resection.

The purpose of the present study was to determine the response of the porcine coeliac-superior mesenteric ganglion complex (CSMG) neurons projecting to the prepyloric area of the porcine stomach to peripheral neuronal damage following partial stomach resection. To identify the sympathetic neurons innervating the studied area of stomach, the neuronal retrograde tracer Fast Blue (FB) was applied to control and partial stomach resection (RES) groups. On the 22nd day after FB injection, following laparotomy, the partial resection of the previously FB-injected stomach prepyloric area was performed in animals of RES group. On the 28th day, all animals were re-anaesthetized and euthanized. The CSMG complex was then collected and processed for double-labeling immunofluorescence. In control animals, retrograde-labelled perikarya were immunoreactive to tyrosine hydroxylase (TH), dopamine ß-hydroxylase (DßH), neuropeptide Y (NPY) and galanin (GAL). Partial stomach resection decreased the numbers of FB-positive neurons immunopositive for TH and DßH. However, the strong increase of NPY and GAL expression, as well as de novo-synthesis of neuronal nitric oxide synthase (nNOS) and leu5-Enkephalin (LENK) was noted in studied neurons. Furthermore, FB-positive neurons in all pigs were surrounded by a network of cocaine- and amphetamine-regulated transcript peptide (CART)-, calcitonin gene-related peptide (CGRP)-, and substance P (SP)-, vasoactive intestinal peptide (VIP)-, LENK- and nNOS- immunoreactive nerve fibers. This may suggest neuroprotective contribution of these neurotransmitters in traumatic responses of sympathetic neurons to peripheral axonal damage.

Free Antropyloric Valve Flap for End-Stage Fecal Incontinence as a Substitute to Permanent Colostomy.

BACKGROUND: Surgical removal of the anal canal and sphincter for carcinoma results in end-stage fecal incontinence (ESFI) and requires a permanent colostomy resulting in significant impact on quality of life. Presently, there are limited options for EFSI. The successful use of pedicled antropyloric valve (APV) based on left gastroepiploic artery as an alternative to permanent colostomy has previously been described. It is based on a long omental pedicle which at times is risky and is difficult to perform. A free APV flap could be the only solution in such cases. We assessed the vascular anatomy for the technical feasibility of a free APV flap, and report the first ever clinical application of free APV flap. METHODS: Bench dissection of 10 pancreaticoduodenectomy specimens was done to delineate the vessels of APV flap. It showed the consistent presence of right gastroepiploic and infrapyloric vessels in all specimens with sufficient diameters. After the technical feasibility, a free APV Flap transposition to perineum was done in a patient, where pedicled transposition was not feasible. RESULTS: The free APV flap with vagus nerve branch was harvested without extensive dissection along the greater curvature of stomach. A tension free anastomosis was achieved between the epiploic and left colic vessels. The flap survived well and had a definite tone on digital examination. It was evaluated by radiological and manometric methods. CONCLUSIONS: APV flap for EFSI can be done as a free flap with distinct advantages and it has the potential of becoming popular options for EFSI.

Surgical techniques to prevent reflux esophagitis in proximal gastrectomy reconstructed by esophagogastrostomy with preservation of the lower esophageal sphincter, pyloric and celiac branches of the vagal nerve, and reconstruction of the new His angle for early proximal gastric cancer.

PURPOSE: This article describes the surgical techniques to prevent reflux esophagitis (RE) after proximal gastrectomy reconstructed by esophagogastrostomy (PGE) preservation of the lower esophageal sphincter (LES) and both pyloric and celiac branches of the vagal nerve (PCVN), and reconstruction of the new His angle (HA) for early proximal gastric cancer (PGC). METHODS: Twenty patients after PGE were divided into 2 groups (group A: 10 patients without preserved LES and PCVN for advanced PGC; group B: 10 patients with preserved LES and PCNV and the addition of a new HA for early PGC). A postoperative interview on gastroesophageal reflux disease (GERD) and satisfaction with this procedure and the collection of endoscopic findings for RE and stasis of the remnant stomach (SRS) were conducted 1 year after PGE in groups A and B. RESULTS: The rates of proton pump inhibitor administration and the symptoms of GERD, RE and SRS in group A were significantly higher than those in group B (p = 0.0433, p = 0.0190, p = 0.0253, p = 0.0190, respectively). Seven out of 10 patients in group A voiced dissatisfaction. Patients in group B were significantly more satisfied with this procedure than those in group A (p = 0.0010). CONCLUSION: This method is useful for preventing postoperative GERD including RE in early PGC patients.

Dynamics of signal propagation and collision in axons.

Long-range communication in the nervous system is usually carried out with the propagation of action potentials along the axon of nerve cells. While typically thought of as being unidirectional, it is not uncommon for axonal propagation of action potentials to happen in both directions. This is the case because action potentials can be initiated at multiple "ectopic" positions along the axon. Two ectopic action potentials generated at distinct sites, and traveling toward each other, will collide. As neuronal information is encoded in the frequency of action potentials, action potential collision and annihilation may affect the way in which neuronal information is received, processed, and transmitted. We investigate action potential propagation and collision using an axonal multicompartment model based on the Hodgkin-Huxley equations. We characterize propagation speed, refractory period, excitability, and action potential collision for slow (type I) and fast (type II) axons. In addition, our studies include experimental measurements of action potential propagation in axons of two biological systems. Both computational and experimental results unequivocally indicate that colliding action potentials do not pass each other; they are reciprocally annihilated.

Neuromodulation of perineally transposed antropylorus with pudendal nerve anastomosis following total anorectal reconstruction in humans.

BACKGROUND: We have reported perineal antropyloric segment transposition with its pudendal innervation as a replacement for anal sphincter. Our aim herein was to neuromodulate this segment by electrical stimulation. METHODS: Eight patients with a permanent colostomy underwent perineal antropyloric segment transposition followed by neural anastomosis of its anterior vagus branch to pudendal nerve branch in the perineum. Perineal antropyloric graft was assessed for its functional integrity and electrophysiological effects. Nerve stimulation was done by surface stimulation technique, using a customized stimulation protocol for smooth muscle. Antral pressures were recorded on voluntary attempts and on nerve stimulation with simultaneous concentric needle electromyography of the perineal antropylorus. KEY RESULTS: The antral segment showed slow spontaneous contractions (2-3/min) on digital examination, endoscopy, and electrophysiology. Stimulated antropyloric electromyography showed a latency of 2-5 s with a differential rise in amplitude (mean range 58.57-998.75 µV) according to the frequency of stimulation (range 10-150 Hz). An average latency of 10 s in relation to rise in the antral pressure was observed on pudendal nerve stimulation. Triggering of the intrinsic rhythm was observed in patients where it was initially absent. Voluntary attempts at contraction also showed a rise in perineally transposed antral pressure. CONCLUSIONS & INFERENCES: Spontaneous rhythm, its generation after electrical stimulation, and response to voluntary contraction demonstrates the viability and functional reinnervation of the perineally transposed antropyloric segment. Rise in pressure on electrical stimulation shows evidence for its neuromodulation.

Many parameter sets in a multicompartment model oscillator are robust to temperature perturbations.

Neurons in cold-blooded animals remarkably maintain their function over a wide range of temperatures, even though the rates of many cellular processes increase twofold, threefold, or many-fold for each 10°C increase in temperature. Moreover, the kinetics of ion channels, maximal conductances, and Ca(2+) buffering each have independent temperature sensitivities, suggesting that the balance of biological parameters can be disturbed by even modest temperature changes. In stomatogastric ganglia of the crab Cancer borealis, the duty cycle of the bursting pacemaker kernel is highly robust between 7 and 23°C (Rinberg et al., 2013). We examined how this might be achieved in a detailed conductance-based model in which exponential temperature sensitivities were given by Q10 parameters. We assessed the temperature robustness of this model across 125,000 random sets of Q10 parameters. To examine how robustness might be achieved across a variable population of animals, we repeated this analysis across six sets of maximal conductance parameters that produced similar activity at 11°C. Many permissible combinations of maximal conductance and Q10 parameters were found over broad regions of parameter space and relatively few correlations among Q10s were observed across successful parameter sets. A significant portion of Q10 sets worked for at least 3 of the 6 maximal conductance sets (∼11.1%). Nonetheless, no Q10 set produced robust function across all six maximal conductance sets, suggesting that maximal conductance parameters critically contribute to temperature robustness. Overall, these results provide insight into principles of temperature robustness in neuronal oscillators.

Region-specific differences in the human myenteric plexus: an immunohistochemical study using donated elderly cadavers.

PURPOSE AND METHODS: To identify site-dependent and individual differences in neuronal nitric oxide synthase (nNOS)-positive nerves of the myenteric plexus, we examined full-thickness walls of the stomach, pylorus, duodenum, ileum, colon, and rectum in 7 male and 8 female cadavers (mean ages, 80 and 87 years, respectively). RESULTS: The areas occupied by nNOS-positive nerve fibers in the myenteric plexus were fragmentary and overlapped with areas occupied by vasoactive intestinal polypeptide-positive fibers. The nNOS-positive fiber-containing areas per 1-mm length of intermuscular space tended to be larger at more anal sites, with positive areas four times greater in the rectum than in the stomach. Interindividual differences in rectal areas were extremely large, ranging from 0.017 mm(2) in one 80-year-old man to 0.067 mm(2) in another 80-year-old man. Similarly, the numbers of nNOS-positive ganglion cell bodies per 1-mm length in the rectum ranged from 4 to 28. These areas and numbers were weakly correlated (r = 0.62; p = 0.02). Interindividual differences in the rectum appeared not to depend on either age or gender. CONCLUSIONS: Anatomic studies using donated cadavers carried the advantage of obtaining any parts of intestine within an individual, in contrast to surgically removed specimens. We speculated excess control of evacuation with laxatives as one of causes of atrophy of the rectal myenteric plexus.

Neurovascular antropylorus perineal transposition using inferior rectal nerve anastomosis for total anorectal reconstruction: preliminary report in humans.

BACKGROUND: Technical feasibility of inferior rectal nerve anastomosis to the anterior vagus branch of the perineally transposed antropyloric valve for total anorectal reconstruction has been previously demonstrated in cadavers. To the best of our knowledge, the present study is the first report of using this procedure in humans. METHODS: Eight patients [mean age 35.5 years (range 15-55 years); (male/female = 7:1)] underwent the procedure. The antropyloric valve with its anterior vagus branch was mobilized based on the left gastroepiploic arterial pedicle. The antral end was anastomosed to the distal colon. The anterior vagus nerve was anastomosed by epineural technique to the inferior rectal nerve in the perineum. A diverting proximal colostomy was maintained for 6 months. Anatomical integrity of the graft (on magnetic resonance imaging scans), its arterial pedicle (on computed tomography angiogram) and neural continuity (on ultrasound and pyloric electromyography) were assessed. Functional assessment was performed using barium retention studies, endoscopy, manometry and fecal incontinence scores. RESULTS: Tension-free end-to-end anastomosis of the anterior vagus nerve to the right (n = 7) and left (n = 1) inferior rectal nerve was achieved. An intact left gastroepiploic pedicle, a healthy graft and neural continuity were visualized on perineal ultrasound. Electromyographic activity was noticed on neural stimulation. Endoscopy and barium studies showed voluntary antral contraction and contrast retention, respectively, in all patients. The mean resting and squeeze pressures were 26.25 mmHg (range 16-62 mmHg) and 50.25 mmHg (range 16-113 mmHg), respectively. St. Mark's incontinence scores varied between 7 and 12. There were no major surgical complications. CONCLUSIONS: Pudendal (inferior rectal) innervation of the perineally transposed antropylorus in total anorectal reconstruction is feasible and may improve outcomes in selected patients with end-stage fecal incontinence.

Dopaminergic tone regulates transient potassium current maximal conductance through a translational mechanism requiring D1Rs, cAMP/PKA, Erk and mTOR.

BACKGROUND: Dopamine (DA) can produce divergent effects at different time scales. DA has opposing immediate and long-term effects on the transient potassium current (IA) within neurons of the pyloric network, in the Panulirus interruptus stomatogastric ganglion. The lateral pyloric neuron (LP) expresses type 1 DA receptors (D1Rs). A 10 min application of 5-100 µM DA decreases LP IA by producing a decrease in IA maximal conductance (Gmax) and a depolarizing shift in IA voltage dependence through a cAMP-Protein kinase A (PKA) dependent mechanism. Alternatively, a 1 hr application of DA (≥5 nM) generates a persistent (measured 4 hr after DA washout) increase in IA Gmax in the same neuron, through a mechanistic target of rapamycin (mTOR) dependent translational mechanism. We examined the dose, time and protein dependencies of the persistent DA effect. RESULTS: We found that disrupting normal modulatory tone decreased LP IA. Addition of 500 pM-5 nM DA to the saline for 1 hr prevented this decrease, and in the case of a 5 nM DA application, the effect was sustained for >4 hrs after DA removal. To determine if increased cAMP mediated the persistent effect of 5nM DA, we applied the cAMP analog, 8-bromo-cAMP alone or with rapamycin for 1 hr, followed by wash and TEVC. 8-bromo-cAMP induced an increase in IA Gmax, which was blocked by rapamycin. Next we tested the roles of PKA and guanine exchange factor protein activated by cAMP (ePACs) in the DA-induced persistent change in IA using the PKA specific antagonist Rp-cAMP and the ePAC specific agonist 8-pCPT-2'-O-Me-cAMP. The PKA antagonist blocked the DA induced increases in LP IA Gmax, whereas the ePAC agonist did not induce an increase in LP IA Gmax. Finally we tested whether extracellular signal regulated kinase (Erk) activity was necessary for the persistent effect by co-application of Erk antagonists PD98059 or U0126 with DA. Erk antagonism blocked the DA induced persistent increase in LP IA. CONCLUSIONS: These data suggest that dopaminergic tone regulates ion channel density in a concentration and time dependent manner. The D1R- PKA axis, along with Erk and mTOR are necessary for the persistent increase in LP IA induced by high affinity D1Rs.

Coordination of distinct but interacting rhythmic motor programs by a modulatory projection neuron using different co-transmitters in different ganglia.

While many neurons are known to contain multiple neurotransmitters, the specific roles played by each co-transmitter within a neuron are often poorly understood. Here, we investigated the roles of the co-transmitters of the pyloric suppressor (PS) neurons, which are located in the stomatogastric nervous system (STNS) of the lobster Homarus americanus. The PS neurons are known to contain histamine; using RT-PCR, we identified a second co-transmitter as the FMRFamide-like peptide crustacean myosuppressin (Crust-MS). The modulatory effects of Crust-MS application on the gastric mill and pyloric patterns, generated in the stomatogastric ganglion (STG), closely resembled those recorded following extracellular PS neuron stimulation. To determine whether histamine plays a role in mediating the effects of the PS neurons in the STG, we bath-applied histamine receptor antagonists to the ganglion. In the presence of the antagonists, the histamine response was blocked, but Crust-MS application and PS stimulation continued to modulate the gastric and pyloric patterns, suggesting that PS effects in the STG are mediated largely by Crust-MS. PS neuron stimulation also excited the oesophageal rhythm, produced in the commissural ganglia (CoGs) of the STNS. Application of histamine, but not Crust-MS, to the CoGs mimicked this effect. Histamine receptor antagonists blocked the ability of both histamine and PS stimulation to excite the oesophageal rhythm, providing strong evidence that the PS neurons use histamine in the CoGs to exert their effects. Overall, our data suggest that the PS neurons differentially utilize their co-transmitters in spatially distinct locations to coordinate the activity of three independent networks.